IDT8N4SV76 Data Sheet LVDS FREQUENCY PROGRAMMABLE VCXO
Factory Datasheet. Contains Confidential Information. Do not send to customers.
Factory Datasheet. Contains Confidential Information. Do not send to customers.
IDT8N4SV76CCD
REVISION B NOVEMBER 20, 2013 4 ©2013 Integrated Device Technology, Inc.
Principles of Operation
The block diagram consists of the internal 3rd overtone crystal and
oscillator which provide the reference clock f
XTAL
of 114.285MHz.
The PLL includes the FemtoClock® VCO along with the Pre-divider
(P), the feedback divider (M) and the post divider (N). The P, M, and
N dividers determine the output frequency based on the f
XTAL
reference. The feedback divider is fractional supporting a huge
number of output frequencies. Internal registers are used to hold up
the factory pre-set configuration setting. The P, M, and N frequency
configurations support an output frequency range 15.476MHz to
866.67MHz and 975MHz to 1,300MHz.
The devices use the fractional feedback divider with a delta-sigma
modulator
for noise shaping and robust frequency synthesis
capability. The relatively high reference frequency minimizes phase
noise generated by frequency multiplication and allows more efficient
shaping of noise by the delta-sigma modulator. The output frequency
is determined by the 2-bit pre-divider (P), the feedback divider (M)
and the 7-bit post divider (N). The feedback divider (M) consists of
both a 7-bit integer portion (MINT) and an 18-bit fractional portion
(MFRAC) and provides the means for high-resolution frequency
generation. The output frequency f
OUT
is calculated by:
f
OUT
f
XTAL
1
PN
------------- MINT
MFRAC 0.5+
2
18
-------------------------------------+=
Frequency Configuration
An order code is assigned to each frequency configuration and the
VCXO pull-range programmed by the factory (default frequencies).
For more information on the available default frequencies and order
codes, please see the Ordering Information Section in this document.
For available order codes, see the FemtoClock NG Ceramic-Package
XO and VCXO Ordering Product Information document.
For more information on programming capabilities of the device for
custom
frequency and pull-range configurations, see the FemtoClock
NG Ceramic 5x7 Module Programming Guide.
